The present invention relates to a method and apparatus for measuring the length of a waste log and/or for measuring the weight of the waste log while compacting and transferring the waste log for transport.
Waste compaction devices are generally known. Such devices are commonly used at waste transfer stations to receive solid waste material and to compact the solid waste material for transport. Some compaction devices, known as tamping devices, are adapted for use on trailers which transport the waste material to a disposal site (e.g., a land fill, incinerator, and the like). Initially, loose waste material is loaded onto the trailer, and then the tamping device is used to compact the loose waste material while it is already on the trailer. Such tamping devices, however, require the trailer to be present during the entire compaction operation. Also, because the trailer tamping device presses the waste material against the trailer's walls and/or floor, the trailer is subjected to very strong forces and must be reinforced to reduce the likelihood of failure. Such forces nevertheless tend to reduce the useful life of the trailer, when compared to trailers that receive and transport the waste material after compaction only.
In order to avoid the problems associated with tamping devices, efforts have been made to provide compaction devices which perform the compaction process internally and transfer the compacted waste material in log form to the trailer. Such compaction devices generally avoid the problem of exposing the trailer to the compaction forces.
A primary object of compaction devices is to optimize the density of the waste log (i.e., optimize the amount of waste material per unit volume of the waste log). Some conventional compaction devices therefore contain a powerful hydraulic ram which moves through a cylinder to compress the waste material. In particular, the waste material is loaded into the cylinder, and the ram is actuated to compress the waste material and reduce or eliminate voids therein. After compression, the waste material is pushed onto the trailer for transportation to the disposal site. Conventional compaction devices, however, lack any reliable way of automatically determining the length of the waste log and/or weight of the waste log.
Since trailers have limited dimensions, it is desirable to provide a way of automatically determining when the compressed waste log has reached a predetermined maximum length which a particular trailer can accommodate. If the length cannot be readily determined and the waste log ends up being too long, it may become jammed in the trailer, making unloading difficult, time consuming, and expensive. If the waste log is shorter than what the trailer can accommodate, then the trailer's capacity is not being used to its fullest extent. In this regard, the trailer is not being used as efficiently as possible. The waste material left behind eventually must be transported to the disposal site, thus requiring additional trips to the disposal site. This results in unnecessary expenditures of fuel, unnecessary wear-and-tear on the trailers and the tractors which pull them, as well as increased labor costs (drivers, mechanics, and the like). There is consequently a need in the art for a way of automatically determining when the compressed waste log has reached the predetermined maximum length so that the waste log can be cut-off automatically at that length and transported efficiently to the disposal site.
Trailers also have weight restrictions which are imposed by the trailer manufacturer, by law, and/or by a transportation authority (e.g., state departments of transportation or a federal agency). If the waste log becomes too heavy, unloading of some of the compacted waste may become necessary in order to comply with the weight restrictions of the trailer or to avoid a dangerous situation. Unloading of the excess compacted waste, however, is generally time-consuming and highly impractical. Similarly, if the waste log is lighter than what the trailer can accommodate, then the trailer's capacity is not being used to its fullest extent. The waste material left behind eventually must be transported to the disposal site, thus requiring additional trips to the disposal site. This also results in unnecessary expenditures of fuel, unnecessary wear-and-tear on the trailers and the tractors which pull them, as well as increased labor costs. There is consequently a need in the art for a way of automatically determining when the compressed waste log has reached a predetermined maximum weight, to permit termination of the flow of waste material into the waste log and transfer of the waste log onto the trailer.